Ruptured berry aneurysm, stroke, aging, Alzheimer's disease and Parkinson's disease may involve oxidative stress induction in the brain. Previous model systems have used toxins to explore oxidative stress in the brain that are too specific, focussing on the dopaminergic neurons especially. However, the biochemical consequences of oxidative stress in neurons and cells that are not dopaminergic are less well studied. The current proposal will use a new model employing t-butylhydroperoxide given intracerebroventricularly which should not be specific for dopaminergic neurons. t-Butylhydroperoxide is a direct acting and potent oxidative stress inducing agent. Preliminary evidence demonstrates that glutathione is depleted and glutathione disulfide levels are enhanced in every brain region examined after t-butylhydroperoxide administration. However, these changes are different in magnitude in various regions which may indicate that some brain regions are more susceptible to oxidative stress than others. Time course and dose response curves have already been performed and are reported in the preliminary evidence. The first specific aim will explore the ability of t-butylhydroperoxide to penetrate into specific brain regions. HPLC or GC/MS techniques will be used to quantitate t-butylhydroperoxide levels. The second specific aim will investigate t-butylhydroperoxide induced neuropathology and alterations in specific neurotransmitter systems. Neuropathology will be examined at the light and electron microscopic levels. Alterations in neurotransmitters will employ HPLC, radiochemical and other techniques. Various defensive enzymes will be examined to see if t-butylhydroperoxide administration alters their activities. These enzymes are glutathione synthetase, glutathione peroxidase and glutathione disulfide reductase, all of which will be investigated with standard spectrophotometric or spectrofluorometric techniques. NADPH levels may be depleted by t-butylhydroperoxide due to the action of glutathione disulfide reductase, in part. Levels of NADPH and NADP+ will be examined by HPLC following t-butylhydroperoxide administration. This approach will yield important information about oxidative stress in the brain.